Tungsten free alloy

ABSTRACT

High temperature nickel-base alloy containing a base of nickel and about 5.5 percent aluminum, about 0.02 percent boron, about 0.18 percent carbon, about 15 percent cobalt, about 10 percent chromium, about 1.5 percent hafnium, about 3 percent molybdenum, about 4.0 percent titanium, about 1 percent vanadium, about 0.1 percent zirconium.

United States Patent [191 Hockin et al.

m, 3,753,697 V I [451 Aug. 21, 1.973

[ TUNGSTEN FREE ALLOY 75 Inventors: John Hockin; Carl B. Lund, both of Arlington Heights; Wilbert P. Danesi, Deerfield, all of Ill.

[73] Assignee: Martin Marietta Corporation, New

York,N.Y. v

[22] Filed: Jan. 18, 1971 [21] App]. No.: 107,338

[52] U.S. Cl. 75/171, 148/32.5 [51] Int. Cl. C22c 19/00 [58] Field of Search 75/171, 170; 148/32,

[56] References Cited UNITED STATES PATENTS 3,479,157 11/1969 Richards et al 75/171 3,615,377 10/1971 Quigg et al. 75/171 Primary Examiner-Richard 0. Dean Attorney-John A. Crowley, Jr. and Francis J. Mulligan, Jr.

[5 7] ABSTRACT High temperature nickel-base alloy-containing a base of nickel and about 5.5 percent aluminum, about 0.02' percent boron, about 0.18 percent carbon, about 15 percent cobalt, about 10 percent chromium, about 1.5 percent hafnium, about 3 percent molybdenum, about 4.0 percent titanium, about 1 percent vanadium, about 0.1 percent zirconium.

4 Claims, 2 Drawing Figures PATENTEBAUGZI ma 3.753591 IOOOX INVENTORS JOHN HOCKIN TUNGSTEN FREE ALLOY HISTORY OF THE ART AND PROBLEM In US. application, Ser. No. 725,074, filed Apr. 29, 1968, now abandoned it was disclosed broadly that inclusion of hafnium in cast, nickel-base alloys improved the ductility of such alloys at intermediate temperatures of about 1,400F. (760C). The present invention is concerned with a particular type of nickel-base casting alloy which is similar to Alloy E disclosed in US. application, Ser. No. 725,074, filed Apr. 29, 1968, now abandoned and has as its object the provision of highly improved alloys and castings made of said alloys suitable for use in gas turbine and other areas of utility involving exposure to high stress at a range of high temperatures.

It is an object of the present invention to provide novel highly improved alloys. 1

It is another object of the present invention to provide highly improved castings made of the novel alloy.

Other objects and advantages will become apparent.

from the following description taken in conjunction with the drawing which shows in FIGS. 1 and 2 the microstructure of the highly improved alloys of the present invention.

DESCRIPTION Generally speaking, the present invention contemplates niclel-base alloys containing alloying elements in ranges of percent by weight as set forth in Table I.

TABLE I Element Broad Range Advantageous Range A1 4.7 6.2 5.0 6.0 B 0.002 0.05 0.002 0.03 C 0.10 0.25 0.15 0.20 Co 5 20 19 Cr 8.5 12 9 11 Hf 0.8 3 1.0 2.0 M0 1.5 4 2 4 Ni Balance E. Balance E. Ti 3.75 4.5 3.8 4.4 V 0 1.5 0.75 1.25 Zr 0 0.25 0.01 0.15

The alloys of the present invention are advanta geously made up using as pure materials as are commercially feasible. The nickel content set forth in Table I as Balance E." is essentially the balance of the alloy and includes small amounts of impurities and incidental elements which do not detrimentally affect the basic and novel characteristics of the alloy. Those skilled in the art will appreciate that metals such as lead, bismuth and the like, metalloids such as arsenic and non-metals such as phosphorus, sulfur, oxygen and the like are highly detrimental to nickel-base alloys of the kind disclosed herein and should be rigidly excluded.

It is highly advantageous to melt and cast the alloys of the invention under high vacuum and to employ current state of the art techniques of investment casting to provide cast hardware such as turbine blades for gas turbine engines. When cast in such a manner, the alloys of the present invention exhibit a microstructure which is substantially different from the microstructure of Alloy E of [1.5. application Ser. No. 725,074, filed Apr. 29, 1968, now abandoned as modified with hafnium. Alloy E modified with hafnium contains, in percent by weight, about 0.18 percent carbon, about 10 percent chromium, about 15 percent cobalt, about 3 percent molybdenum, about 4.7 percent titanium, about 5.5 percent aluminum, about 0.014 percent boron, about (i 06 percent zirconium, about 1.0 percent vanadium, about 1.5 percent hafnium with the balance being essentially nickel. For all practical purposes Alloy E differs from the alloy of Range A" only in containing 4.7 percent titanium as opposed to the 4.0 percent titanium in the alloy of the advantageous range. The microstructure of both alloys show a basic gamma matrix having gamma-prime phase and carbides dispersed therethrough. The microstructures differ in that in modified Alloy E" the gamma-prime phase appears as cubic particles whereas in the alloy of thepresent invention the particles of this phase tend to be elongated. 1n the microstructure of modified Alloy E there are discrete islands of eutectic gamma-prime phase. With the alloy of the present invention islands of eutectic gamma-prime phase are non-discrete and tend to blend in with the matrix. Again, with modified Alloy 13" discrete grain boundaries can be distinguished whereas with the alloy of the present invention grain boundaries can hardly be distinguished. The drawing shows the microstructure of the alloy of the present invention as brought out by etching with a reagent made up by mixing 30 m1. of glycerol, 8 ml. of concentrated nitric acid and 6 ml. of 48 percent hydrofluoric acid. The drawing presents magnifications of 250 X in FIG. 2 and 1000 X in FIG. 1 and illustrates the points of difference mentioned. It has been noted that the microstructure as depicted in the drawing is associated with a reduction in titanium content from the level of modified Alloy .E" and that when this microstructure is obtained bythe least reduction titanium content necessary to produce it, there are obtained cast alloys having an optimum combination of mechanical characteristics of engineering significance.

Levels of mechanical characteristics obtainable by alloys of the present invention are exemplified in the tables following Table 11. The compositions of specific alloys within and without the ambit of the invention are set forth (in percent by weight) in Table 11.

TABLE II 1 Element Example Alloy E (Mod) Alloy X Al 5.54 5.5 5.55 H 0.019 0.021 0.013 C 0.18 0.17 0.17 Co 15.10 14.9 15.2 Cr 10.3 10.0 10.5 Hf 1.48 1.34 1.53 Mo 3.11 3.03 3.06 Ni Bal. Bal. Bsl. Ti 3.92 4.55 3.68 V 1.05 0.99 0.95 Zr 0.10 0.08 0.09

Each of the aforelisted alloys were melted and cast under vacuum to provide cast-to-size, 0.250 inch (6.35 mm.) test bars. These test bars were subjected to room temperature tensile tests and creep-rupture tests at 1,800F. (982C.) and 1,400F. (760C) In addition. castings of turbine blades of the configuration employed in the Pratt-Whitney J'IBD gas turbine engine were made with Alloy X and the alloy of the present invention. Test samples were machined from these castings and subjected to room temperature tensile tests andcreep-rupture tests at 1,400'F. (760C), 1,600F. (872C) and 1,800'F. (982C) All of these tests show that the alloy of the present invention exhibits mechanical characteristics substantially superior to those of comparative alloys outside the present invention. The results of room temperature tensile tests on cast-to-size specimens are set forth in Table 1'11.

i TABLE 111' T Ultimate tensile 0.2% yield strength strength Alloy K.s.l. kip/mill. K.s.i. K|.!./l1lll1.-' percent percent Alloy l'l (Mn(l.).. 139.3 lll'i 1113.7 82.2 14.11 17.3 Exmllplo 101.15 113. 4 1211. i 110.8 11. 5 14.11 lll).(l 1211.1: 144.8 ll.5 16.2

Alloy X 150.5

Table [11 shows that the alloy of the present invention exhibits at room temperature (77F.) (C.) higher tensile strength than modified Alloy E along with a higher degree of ductility as indicated by percentage of elongation. Table III also shows that the alloy of the present invention exhibits a peak of room temperature tensile characteristics.

l,600.F. and 1,800F. as compared to Alloy X when both are tested in the form of specimens cut from cast hardware. The alloy of the present invention exhibits lives at 1,600F. and 1,800F. (when tested in this manner) similar to those which would be expected of Alloy E and modified Alloy E when tested under similar conditions. Specific data obtained on specimens of Alloy Table IV sets forth creep-rupture characteristics of 15 E cut from east hardware and tested as shown in Table cast-to-size test specimens at both 1400F. (760C.) V shows lives-to-rupture at 1,600 F. and 1,800F. to be and 1800F. (982C). 321.8 hours and 262.2 hours, respectively.

TABLE 1v 5 Red. ill Time Elongation area Test condition Specimen (hours) (percent) (percent) ModifiedAlloyE 63.!) 7.0 13.2 27 k.s.i.nt1,800 F. (18.05 kpzjnlln. at 082 C.) Example 47. 11 8.0 16. 8 Alloy x 2s. 6 10.0 14. fl Modified Alloy 67.2 e 1.90 4.0 1 0 k.s.l. llt1,400 I". (63.3 kgJmmJ' at 760 C.) Example 211. 8 B 4. 34 b 5.0 Alloy X 203. 3 a 5. 52 h 6. 5

- Percent prior creep. h Percent elongation.

TABLE V Example Alloy X Room Temperature Tensile U.T.S. (kai) 138.4 136.2 U.T.S. (kh/mm') 97.3 95.8 Y.S. (ksi) 108.8 104.5 Y.S. (k /mm') 76.6 73.5 Elong. 4. 10.6 13.5 R.A. 17.6 21.4 Creep Ru turc (1400' .lkli) Litc (hours) 177.9 169.2 (760C./59.8 kg/mm') Elong. (1:) 4.6 4.1 Prior Creep (70) 3.9 3.15 R.A. 9.7 4.1 Creep Ru ture (1600' ./45.0 kri) Life (hours) 444.5-463.0 357.2 (871C./3l.6 lag/mm) Elong. 10.1-9.3 8.4 Prior Creep 7.26-8.16 7.32 R.A. 21.4-106 17.4 Creep Ru ture (1 00 ./20.0 kill) Life (hours) 230.2-269.1 160.4 (982C./14.06

kg/mm') Elong. 7.8-4.7 14.9 R.A. 9.6-8.2 17.7

While the 'pr''s'fifiiventibn' has been described in conjunction with advantageous embodiments, those skilled in the art will recognize that modifications and variations may be resorted to without departing from the spirit and scope of the invention. Such modifications and variations are considered to be within the purview and scope of the invention.

We claim:

1. A cast alloy consisting in percent by weight esssentially of about 4.7 percent to about 6.2 percent aluminum, about 0.002 percent to about 0.05 percent boron, about 0.10 percent to about 0.25 percent carbon, about 5 percent to about 20 percent cobalt, about 8.5 percent to about 12 percent chromium, about 0.8 percent to about3 percent hafnium, about 1.5 percent to about 4 percent molybdenum, about 3.75 percent to about 4.5 percent titanium, up to about 1.5 percent vanadium, up to about 0.25 percent zirconium with the balance being essentially nickel.

2. A cast alloy as in claim 1 containing 5 percent to 6 percent aluminum, 0.002 percent to 0.03 percent boron, 0.15 percent to 0.20 percent carbon, 10 percent to 19 percent cobalt, 9 percent to 11 percent chromium, 1 percent to 2 percent hafnium, 2 percent to 4 percent molybdenum, 3.8 percent to 4.4 percent titanium, 0.75 percent to 1.25 percent vanadium and 0.01 percent to 0.15 percent zirconium.

3. A vacuum-cast turbine blade made of the alloy of claim 1.

4. A vacuum-cast turbine blade made of the alloy of claim 2.

i i 4 i t Patent No 3,753,697 Dated August 21, 1973 Inventor It is certified that error appears in the above-identified patent and that: said Letters Patent are hereby corrected as shown below:

Column 1, 1ine29, V "niclel-baseflshould be nickel-base Column 2, line 31, after "reduction" the word of is omitted.

Column 3, line 42,,fi rst headingin Table v Test Condition is omitted in first column.

Signed and sealed this lst day of January 197M.

XSEAL) Attest:

EDWARD MEDETGHER R. RENE D. TEGTMEYER I I Attesting Officer Acting Commissioner of Patents ij-r ssw, 904050 (10-69) UsCOMM-DC 60376-P69 h u.s. eovnuuzm' num'mc OFFICE :19" 0-3Il-J3l j 

2. A cast alloy as in claim 1 containing 5 percent to 6 percent aluminum, 0.002 percent to 0.03 percent boron, 0.15 percent to 0.20 percent carbon, 10 percent to 19 percent cobalt, 9 percent to 11 percent chromium, 1 percent to 2 percent hafnium, 2 percent to 4 percent molybdenum, 3.8 percent to 4.4 percent titanium, 0.75 percent to 1.25 percent vanadium and 0.01 percent to 0.15 percent zirconium.
 3. A vacuum-cast turbine blade made of the alloy of claim
 1. 4. A vacuum-cast turbine blade made of the alloy of claim
 2. 